Minimizing ECG Artifact

Minimizing motion artifact Mild skin abrasion with fine sandpaper or gritty gel effectively minimizes all types of motion and electrostatic artifact (medical products are available for this)

Respiration: Low frequency (0.4–2 Hz)

� Check for dried gel � Abrade skin � Have patient take deep

breath, let half out and hold while acquiring the ECG

Patient Movement: Low frequency (1–3 Hz)

� Check for dried gel � Abrade skin � Have patient lie still and

stop talking

Transport: Medium frequency (3–15 Hz)

� Check for dried gel � Abrade skin � Stop ambulance to get

clean ECG

Muscle Tremor: High frequency (20-150 Hz) and/or medium frequency (3-5 Hz)

Minimizing muscle artifact Skin prep will not help, but other techniques can help

Muscle Tension: High frequency (20-150 Hz)

� Assure that limbs are supported and the patient is lying flat

� Ask the patient to relax � Consider pain Rx if pain is the likely cause

� Reducing the upper cutoff frequency filter from 150 to 40 Hz reduces muscle artifact

� If shivering, cover with a blanket � Move limb electrode elsewhere on limb

to avoid culprit muscle � Abrade skin if there is motion artifact

Intermittent or missing leadsIntermittent Lead

� Check for dry electrodes � Shave or clip hair from electrode site if excessive hair is present � Alcohol wipe if skin is oily or sweaty � Check for intermittent cable failure by trying a different cable � For intermittent connector on ECG device, service call needed

Missing Lead

� Check for dry electrodes � Verify that electrode and lead wire are attached to patient � Replace worn or broken lead wire or patient cable � For worn or broken connector on ECG device, service call needed

Identifying the culprit electrode � If the artifact is in leads I and II but not III, the RA electrode is the source � If the artifact is in I and III but not II, the LA electrode is the source � If the artifact is in II and III but not I, the LL electrode is the source � If the artifact is unique to one V lead, its V electrode is the source

ECG artifact nearly always originates from sources unrelated to the monitor. The following are best practice suggestions for minimizing artifact.

Motion artifact Occurs when the skin is stretched, resulting in a change to the skin voltage at the stratum lucidum, the second layer down in the skin

Muscle artifact Generated by skeletal muscles

Electrostatic artifact When an electrostatically charged person moves near the patient or ECG device, cur-rents flow through the high resistance of the stratum corneum (top skin layer) and gener-ate a voltage

Poor contact artifact Caused by dried gel, excessive hair, poor adhesion or when breaks in connectivity occur anywhere between the electrode and the monitor

Electromagnetic Interference (EMI) Generated by items like power lines, cell phones or radios; relatively uncommon

Implanted stimulators Artifact is greatest in leads parallel to the stimulus lead; pacemakers are common but other stimulators are rare

Types of ECG artifact Cause

Minimizing electromagnetic interference (EMI)

Cell Phone or Other Equipment: High frequency

� Identify likely source, turn off or increase distance

� Identify likely source, turn off or increase distance � Inverse square law: increasing the distance to the EMI

source by 10x decreases the artifact to 1/100th � If it happens often, verify that ECG device is set to

correct line frequency filter (50 or 60 Hz) � Skin abrasion and wet gel sometimes solve it

Power Line: High frequency (16.7, 50, 60, 100, 120, 150, 180 Hz)

Implanted pacemakers and stimulators

Paced rhythm: High frequency spikes (>100 Hz) � Change upper cutoff frequency to 150

Hz if you want to increase the visibility of pacemaker spikes

Gastric or other Stimulator: High frequency spikes (>40 Hz) � Look for a lead with low stimulator artifact � Record a 12-lead ECG and select a lead

with low stimulator artifact � Some devices can be temporarily turned

off with a magnet

� Other stimulators include occipital nerve stimulators, deep brain stimulators, sacral nerve stimulators and carotid stimulators

Skin preparation techniques � Choose an ECG electrode site away from areas with a large amount of adipose tissue,

major muscle groups or bony prominences

� Excessive hair should be clipped or shaved y Hair can prevent ECG electrode adhesion to the skin

� Mild skin abrasion with fine sandpaper or gritty gel (medical products are available for this purpose) y Swipe an X with sandpaper to scratch the skin and place the electrode gel on the

center of the X y Skin abrasion minimizes motion artifact, but not muscle artifact

� Dry towel or gauze pad skin rub y Useful for patients with sweaty or oily skin to improve electrode adhesion y Does not reduce motion or muscle artifact

� Isopropyl alcohol wipe y This can help the electrodes stick to the skin, but it does not reduce motion or

muscle artifact

©2015 Physio-Control, Inc., Redmond WA, USA. GDR 3306627_A